Lipopolysaccharide impairs neurodevelopment and induces changes in astroglial reactivity, antioxidant defenses and bioenergetics in the cerebral cortex of neonatal rats.

Neonates have an immature immune system, which increases their vulnerability to infectious agents and inflammatory insults. The administration of the immunostimulatory agent lipopolysaccharide (LPS) has been shown to induce the expression of pro-inflammatory cytokines and cause behavior alterations in rodents at different ages. However, the effects of LPS administration during the neonatal period and its consequences during immune system maturation remain to be elucidated. We showed here that a single intraperitoneal administration of LPS in rats on postnatal day (PND) 7 caused early and variable alterations in TNF-α, S100B and GFAP levels in the cerebral cortex, CSF and serum of the animals, indicating long-term induction of neuroinflammation and astroglial reactivity. However, on PND 21, only GFAP levels were increased by LPS. Additionally, LPS induced oxidative stress and altered energy metabolism enzymes in the cerebral cortex on PND 21, and caused neurodevelopment impairment over time. These data suggest that neuroinflammation induction during the neonatal period induces glial reactivity, oxidative stress and bioenergetic disruption that may lead to neurodevelopment impairment and cognitive deficit in adult life.

Hypoxanthine Induces Neuroenergetic Impairment and Cell Death in Striatum of Young Adult Wistar Rats.

Hypoxanthine is the major purine involved in the salvage pathway of purines in the brain. High levels of hypoxanthine are characteristic of Lesch-Nyhan Disease. Since hypoxanthine is a purine closely related to ATP formation, the aim of this study was to investigate the effect of intrastriatal hypoxanthine administration on neuroenergetic parameters (pyruvate kinase, succinate dehydrogenase, complex II, cytochrome c oxidase, and ATP levels) and mitochondrial function (mitochondrial mass and membrane potential) in striatum of rats. We also evaluated the effect of cell death parameters (necrosis and apoptosis). Wistar rats of 60 days of life underwent stereotactic surgery and were divided into two groups: control (infusion of saline 0.9%) and hypoxanthine (10 µM). Intrastriatal hypoxanthine administration did not alter pyruvate kinase activity, but increased succinate dehydrogenase and complex II activities and diminished cytochrome c oxidase activity and immunocontent. Hypoxanthine injection decreased the percentage of cells with mitochondrial membrane label and increased mitochondrial membrane potential labeling. There was a decrease in the number of live cells and an increase in the number of apoptotic cells by caused hypoxanthine. Our findings show that intrastriatal hypoxanthine administration altered neuroenergetic parameters, and caused mitochondrial dysfunction and cell death by apoptosis, suggesting that these processes may be associated, at least in part, with neurological symptoms found in patients with Lesch-Nyhan Disease.

Chronic Exposure to ß-Alanine Generates Oxidative Stress and Alters Energy Metabolism in Cerebral Cortex and Cerebellum of Wistar Rats.

ß-Alanine occurs naturally in the human central nervous system and performs different functions. It can act as either a neurotransmitter or a neuromodulator, depletion of taurine levels and competitive antagonist of γ-aminobutyric acid (GABA). The ß-amino acid accumulation exerts an important biological function as delay in brain development, oxidative stress and disturbances in energy metabolism, characterized as an inborn error of metabolism classified as ß-alaninemia. We evaluated the effects of the chronic administration of ß-alanine on some parameters of oxidative stress and enzymes of energy metabolism in cerebral cortex and cerebellum of 21-day-old Wistar rats. The animals received peritoneal injections of ß-alanine (300 mg/kg of body weight), and the controls received the same volume (10 µl/g of body weight) of saline solution (NaCl 0.9%), twice a day at 12-h interval, from the 7th to the 21st postpartum day. We observed that ß-amino acid was able to increase the levels of reactive oxygen species (ROS) in the two tissues; however, only in cerebral cortex total content of sulfhydryl was increased. ROS are possibly acting on antioxidant enzymes glutathione peroxidase (GPx) (cerebral cortex and cerebellum) and superoxide dismutase (SOD) (cerebellum) inhibiting their activities. We also evaluated the activities of enzymes of the phosphoryl transfer network, where we observed an increase in hexokinase and cytosolic creatine kinase (Cy-CK) activities; however, it decreased glyceraldehyde 3-phosphate dehydrogenase (GAPDH), pyruvate kinase (PK) and lactate dehydrogenase (LDH) activities, in both tissues. Besides, the ß-alanine administration increased the activities of complex II, complex IV and succinate dehydrogenase (SDH). Those results suggest that the chronic administration of ß-alanine causes cellular oxidative damage, significantly changing the energy metabolism.

A Possible Anti-Inflammatory Effect of Proline in the Brain Cortex and Cerebellum of Rats.

Although many studies show the toxic effects of proline, recently it has been reported some anti-inflammatory effect of this amino acid. Our principal objective was to investigate the effects of proline on the alterations caused by LPS (lipopolysaccharide) administration in the cerebral cortex and cerebellum of young Wistar rats. The animals were divided into four groups: control (0.85% saline); proline, (12.8 µmol of proline/g body weight from day 7 to 13; 14.6 µmol of proline/g body weight from day 14 to 17 and 16.4 µmol of proline/g body weight from day 18 to 21); LPS (1 mg/g body weight); LPS plus proline. The animals were killed at 22 days of age, 12 h after the last injection, by decapitation without anesthesia. The brain cortex and cerebellum were separated for chemical determinations. The effects of proline and LPS in the cerebral cortex and cerebellum on the expression of S100B and GFAP, oxidative stress parameters, enzymes of phosphoryl transfer network activity, and mitochondrial respiration chain complexes were investigated. Two-way ANOVA showed that the administration of proline did not alter the analyzed parameter in cerebral cortex and cerebellum. On the other hand, LPS administration caused a change in these parameters. Besides, the co-administration of proline and LPS showed the ability of Pro in preventing the effects of LPS. These results indicated that LPS induces inflammation, oxidative stress, and alters energy parameters in cerebral cortex and cerebellum of the rats. Moreover, co-administration of Pro was able to prevent these harmful effects of LPS.

Evaluation of Oxidative Stress Parameters and Energy Metabolism in Cerebral Cortex of Rats Subjected to Sarcosine Administration.

Sarcosine is an N-methyl derivative of the amino acid glycine, and its elevation in tissues and physiological fluids of patients with sarcosinemia could reflect a deficient pool size of activated 1-carbon units. Sarcosinemia is a rare inherited metabolic condition associated with mental retardation. In the present study, we investigated the acute effect of sarcosine and/or creatine plus pyruvate on some parameters of oxidative stress and energy metabolism in cerebral cortex homogenates of 21-day-old Wistar rats. Acute administration of sarcosine induced oxidative stress and diminished the activities of adenylate kinase, GAPDH, complex IV, and mitochondrial and cytosolic creatine kinase. On the other hand, succinate dehydrogenase activity was enhanced in cerebral cortex of rats. Moreover, total sulfhydryl content was significantly diminished, while DCFH oxidation, TBARS content, and activities of SOD and GPx were significantly enhanced by acute administration of sarcosine. Co-administration of creatine plus pyruvate was effective in the prevention of alterations provoked by sarcosine administration on the oxidative stress and the enzymes of phosphoryltransfer network. These results indicate that acute administration of sarcosine may stimulate oxidative stress and alter the energy metabolism in cerebral cortex of rats. In case these effects also occur in humans, they may contribute, along with other mechanisms, to the neurological dysfunction of sarcosinemia, and creatine and pyruvate supplementation could be beneficial to the patients.

Chemically induced acute model of sarcosinemia in wistar rats.

In the present study, we developed an acute chemically induced model of sarcosinemia in Wistar rats. Wistar rats of 7, 14 and 21 postpartum days received sarcosine intraperitoneally in doses of 0.5 mmol/Kg of body weight three time a day at intervals of 3 h. Control animals received saline solution (NaCl 0.85 g%) in the same volume (10 mL/Kg of body weight). The animals were killed after 30 min, 1, 2, 3 or 6 h after the last injection and the brain and the blood were collected for sarcosine measurement. The results showed that plasma and brain sarcosine concentrations achieved levels three to four times higher than the normal levels and decreased in a time-dependent way, achieving normal levels after 6 hours. Considering that experimental animal models are useful to investigate the pathophysiology of human disorders, our model of sarcosinemia may be useful for the research of the mechanisms of neurological dysfunction caused by high tissue sarcosine levels.

Creatine and pyruvate prevent the alterations caused by tyrosine on parameters of oxidative stress and enzyme activities of phosphoryltransfer network in cerebral cortex of Wistar rats.

Tyrosine accumulates in inborn errors of tyrosine catabolism, especially in tyrosinemia type II. In this disease caused by tyrosine aminotransferase deficiency, eyes, skin, and central nervous system disturbances are found. In the present study, we investigated the chronic effect of tyrosine methyl ester (TME) and/or creatine plus pyruvate on some parameters of oxidative stress and enzyme activities of phosphoryltransfer network in cerebral cortex homogenates of 21-day-old Wistar. Chronic administration of TME induced oxidative stress and altered the activities of adenylate kinase and mitochondrial and cytosolic creatine kinase. Total sulfhydryls content, GSH content, and GPx activity were significantly diminished, while DCFH oxidation, TBARS content, and SOD activity were significantly enhanced by TME. On the other hand, TME administration decreased the activity of CK from cytosolic and mitochondrial fractions but enhanced AK activity. In contrast, TME did not affect the carbonyl content and PK activity in cerebral cortex of rats. Co-administration of creatine plus pyruvate was effective in the prevention of alterations provoked by TME administration on the oxidative stress and the enzymes of phosphoryltransfer network, except in mitochondrial CK, AK, and SOD activities. These results indicate that chronic administration of TME may stimulate oxidative stress and alter the enzymes of phosphoryltransfer network in cerebral cortex of rats. In case this also occurs in the patients affected by these disorders, it may contribute, along with other mechanisms, to the neurological dysfunction of hypertyrosinemias, and creatine and pyruvate supplementation could be beneficial to the patients.

Assessment of changes in energy metabolism parameters provoked by carbon tetrachloride in Wistar rats and the protective effect of white grape juice.

The objective of this study was to evaluate the effect of organic and conventional grape juices consumption on the behavior of rats and their neuroprotective effect on the activity of brain energy metabolism enzymes in different brain areas of adult rats on the experimental model of hepatic encephalopathy. Male Wistar rats (90-days-old) were treated once a day with conventional or organic white grape juice by gavage for 14 days (7 µL/g). On the 15th day the rats received carbon tetrachloride (CCl4) in a single dose of 3.0 mL/kg. Cerebral cortex, hippocampus and cerebellum were dissected to measure the activity of creatine kinase (CK) and pyruvate kinase (PK). No changes in feeding behavior were observed after the treatment with the grapes juices. However, there was an increase in grooming behavior in the open field test provoked by both juices. CCl4 inhibited CK activity in cerebral cortex and hippocampus of the rats and CCl4 also reduced PK activity in all brain structures studied. Furthermore, both white grape juices prevented the decrease in the activity of CK and PK. Therefore, we can suggest that organic and conventional white grape juices could restore the activity of enzymes with a central role in brain energy metabolism.

Acute exposure to the vinyl chalcogenide 3-methyl-1-phenyl-2-(phenylseleno)oct-2-en-1-one induces oxidative stress in different brain area of rats.

The mechanisms that lead to the onset of organoselenium intoxication are still poorly understood. Therefore, in the present study, we investigated the effect of acute administration of 3-methyl-1-phenyl-2-(phenylseleno)oct-2-en-1-one on some parameters of oxidative stress and on the activity of creatine kinase (CK) in different brain areas and on the behaviour in the open field test of 90-day-old male rats. Animals (n = 10/group) were treated intraperitoneally with a single dose of the organoselenium (125, 250 or 500 µg kg(-1) ), and after 1 h of the drug administration, they were exposed to the open field test, and behaviour parameters were recorded. Immediately after they were euthanized, cerebral cortex, hippocampus and cerebellum were dissected for measurement of thiobarbituric acid reactive substances (TBARS), carbonyl, sulfhydryl, catalase (CAT), superoxide dismutase (SOD) and CK activity. Our results showed that the dose of 500 µg kg(-1) of the organoselenium increased the locomotion and rearing behaviours in the open field test. Moreover, the organochalcogen enhanced TBARS in the cerebral cortex and cerebellum and increased the oxidation of proteins (carbonyl) only in the cerebral cortex. Sulfhydryl content was reduced in all brain areas, CAT activity enhanced in the hippocampus and reduced in the cerebellum and SOD activity increased in all brain structures. The organoselenium also inhibited CK activity in the cerebral cortex. Therefore, changes in motor behaviour, redox state and energy homeostasis in rats treated acutely with organoselenium support the hypotheses that the brain is a potential target for the organochalcogen action. Ltd.

Effects of ß-alanine administration on selected parameters of oxidative stress and phosphoryltransfer network in cerebral cortex and cerebellum of rats.

ß-Alanine is a ß-amino acid derivative of the degradation of pyrimidine uracil and precursor of the oxidative substrate acetyl-coenzyme A (acetyl-CoA). The accumulation of ß-alanine occurs in ß-alaninemia, an inborn error of metabolism. Patients with ß-alaninemia may develop neurological abnormalities whose mechanisms are far from being understood. In this study we evaluated the effects of ß-alanine administration on some parameters of oxidative stress and on creatine kinase, pyruvate kinase, and adenylate kinase in cerebral cortex and cerebellum of 21-day-old rats. The animals received three peritoneal injections of ß-alanine (0.3 mg /g of body weight) and the controls received the same volume (10 µL/g of body weight) of saline solution (NaCl 0.85 %) at 3 h intervals. CSF levels of ß-alanine increased five times, achieving 80 µM in the rats receiving the amino acid. The results of ß-alanine administration in the parameters of oxidative stress were similar in both tissues studied: reduction of superoxide dismutase activity, increased oxidation of 2',7'-dihydrodichlorofluorescein, total content of sulfhydryl and catalase activity. However, the results of the phosphoryltransfer network enzymes were similar in all enzymes, but different in the tissues studied: the ß-alanine administration was able to inhibit the enzyme pyruvate kinase, cytosolic creatine kinase, and adenylate kinase activities in cerebral cortex, and increase in cerebellum. In case this also occurs in the patients, these results suggest that oxidative stress and alteration of the phosphoryltransfer network may be involved in the pathophysiology of ß-alaninemia. Moreover, the ingestion of ß-alanine to improve muscular performance deserves more attention in respect to possible side-effects.

Kinetic studies on the inhibition of creatine kinase activity by 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one in the cerebral cortex of rats.

Tellurium has been used as an industrial component of many alloys and in the electronic industry. Organotellurium compounds can cause poisoning which leads to neurotoxic symptoms such as significant impairment of learning, spatial memory and are potentially neurotoxic to human beings. However, the molecular mechanisms of neurotoxicity of organotellurium compounds are not well understood. Considering that creatine kinase plays a key role in energy metabolism of tissues with intermittently high and fluctuating energy requirements, such as nervous tissue, the main objective of this study was to investigate the mechanisms by which 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one inhibit creatine kinase activity, a key enzyme of energy homeostasis, in the cerebral cortex of 30-day-old Wistar rats. For the kinetic studies, the Lineweaver-Burk plot was used to characterize the mechanisms of enzyme inhibition by 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one. The results suggested that this compound inhibits creatine kinase activity by two different mechanisms: competition with ADP and oxidation of critical sulfhydryl groups for the functioning of the enzyme. The potential for inhibition of creatine kinase to occur in vivo may contribute to the neurotoxicity observed by this organochaocogen.

Effect of histidine administration to female rats during pregnancy and lactation on enzymes activity of phosphoryltransfer network in cerebral cortex and hippocampus of the offspring.

Histidinemia is an inborn error of metabolism of amino acids caused by deficiency of histidase activity in liver and skin with consequent accumulation of histidine in plasma and tissues. Histidinemia is an autosomal recessive trait usually considered harmless to patients and their offspring, but some patients and children born from histidinemic mothers have mild neurologic alterations. Considering that histidinemia is one of the most frequently identified metabolic conditions, in the present study we investigated the effect of L-histidine load to female rats during pregnancy and lactation on some parameters of phosphoryltransfer network in cerebral cortex and hippocampus of the offspring. Pyruvate kinase, cytosolic and mitochondrial creatine kinase activities decreased in cerebral cortex and in hippocampus of rats at 21 days of age and this pattern remained in the cerebral cortex and in hippocampus at 60 days of age. Moreover, adenylate kinase activity was reduced in the cerebral cortex and in hippocampus of the offspring at 21 days of age, whereas the activity was increased in the two tissues at 60 days of age. These results suggest that administration of L-histidine to female rats in the course of pregnancy and lactation could impair energy homeostasis in the cerebral cortex and hippocampus of the offspring. Considering that histidinemia is usually a benign condition and little attention has been given to maternal histidinemia, it seems important to perform more studies in the children born from histidinemic mothers.

Tyrosine impairs enzymes of energy metabolism in cerebral cortex of rats.

Tyrosine levels are abnormally elevated in tissues and physiological fluids of patients with inborn errors of tyrosine catabolism, especially in tyrosinemia type II, which is caused by deficiency of tyrosine aminotransferase and provokes eyes, skin, and central nervous system disturbances. Considering that the mechanisms of brain damage in these disorders are poorly known, in this study, we investigated the in vivo and in vitro effects of tyrosine on some parameters of energy metabolism in cerebral cortex of 14-day-old Wistar rats. We observed that 2 mM tyrosine inhibited in vitro the pyruvate kinase (PK) activity and that this inhibition was prevented by 1 mM reduced glutathione with 30, 60, and 90 min of preincubation. Moreover, administration of tyrosine methyl ester (TME) (0.5 mg/g of body weight) decreased the activity of PK and this reduction was prevented by pre-treatment with creatine (Cr). On the other hand, tyrosine did not alter adenylate kinase (AK) activity in vitro, but administration of TME enhanced AK activity not prevented by Cr pre-treatment. Finally, TME administration decreased the activity of CK from cytosolic and mitochondrial fractions and this diminution was prevented by Cr pre-treatment. The results suggest that tyrosine alters essential sulfhydryl groups necessary for CK and PK functions, possibly through oxidative stress. In case this also occurs in the patients, it is possible that energy metabolism alterations may contribute, along with other mechanisms, to the neurological dysfunction of hypertyrosinemias.

Administration of histidine to female rats induces changes in oxidative status in cortex and hippocampus of the offspring.

Histidinemia is an inherited metabolic disorder biochemically characterized by high concentrations of histidine in biological fluids. Usually affected patients are asymptomatic although some individuals have mental retardation and speech disorders. Considering the high prevalence of histidinemia and the scarce information on the effects of maternal histidinemia on their progeny, we investigated various parameters of oxidative stress in brain cortex and hippocampus of the offspring from female rats that received histidine (0.5 mg/g of body weight) in the course of pregnancy and lactation. At 21 days of age we found a significant increase of thiobarbituric acid reactive substances (TBARS), 2',7'-dihydrodichlorofluorescein oxidation, superoxide dismutase (SOD) activity, catalase (CAT) activity, total sulfhydryls and glutathione (GSH) content in cerebral cortex and hippocampus. We also verified that at 60 days of age, GSH, SOD and total sulfhydryls returned to normal levels in brain cortex, while the other parameters decreased in the same structure. In the hippocampus, at 60 days of age GSH returned to normal levels, CAT persisted elevated and the other parameters decreased. These results indicate that histidine administration to female rats can induce oxidative stress in the brain from the offspring, which partially recovers 40 days after breastfeeding stopped.

Creatine and pyruvate prevent behavioral and oxidative stress alterations caused by hypertryptophanemia in rats.

It is known that the accumulation of tryptophan and its metabolites is related to brain damage associated with both hypertryptophanemia and neurodegenerative diseases. In this study, we investigated the effect of tryptophan administration on various parameters of behavior in the open-field task and oxidative stress, and the effects of creatine and pyruvate, on the effect of tryptophan. Forty, 60-day-old male Wistar rats, were randomly divided into four groups: saline, tryptophan, pyruvate + creatine, tryptophan + pyruvate + creatine. Animals received three subcutaneous injections of tryptophan (2 µmol/g body weight each one at 3 h of intervals) and/or pyruvate (200 µg/g body weight 1 h before tryptophan), and/or creatine (400 µg/g body weight twice a day for 5 days before tryptophan twice a day for 5 days before training); controls received saline solution (NaCl 0.85%) at the same volumes (30 µl/g body weight) than the other substances. Results showed that tryptophan increased the activity of the animals, suggesting a reduction in the ability of habituation to the environment. Tryptophan induced increase of TBA-RS and total sulfhydryls. The effects of tryptophan in the open field, and in oxidative stress were fully prevented by the combination of creatine plus pyruvate. In case these findings also occur in humans affected by hypertryptophanemia or other neurodegenerative disease in which tryptophan accumulates, it is feasible that oxidative stress may be involved in the mechanisms leading to the brain injury, suggesting that creatine and pyruvate supplementation could benefit patients affected by these disorders.

Acute treatment with the organochalcogen 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one produces behavioral changes and inhibition of creatine kinase activity in the brain of rats.

Organotellurium compounds have been synthesized since 1840, but their pharmacological and toxicological properties are still incipient. Therefore, the objective of this study was to verify the effect of acute administration with the organochalcogen 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one on the activity of brain creatine kinase (CK), a key enzyme in energy metabolism, and on behaviors in the open field test of 30-day-old rats. Animals were treated intraperitoneally with a single dose of the organotellurium (125, 250, or 500 µg/kg body weight) and after 55 min of the drug administration the open field test was carried out. Behavior analyses were performed during 5 min and the number of the squares crossed, number of rearing, number of groomings and number of fecal boli were recorded by an observer. Then, the animals were sacrificed and the cerebral cortex, the hippocampus, and the cerebellum were dissected, and CK activity and sulfhydryl content were measured in the brain. The organotellurium increased the ambulation and rearing behaviors in the open field test at doses of 250 and 500 µg/kg. Moreover, the compound inhibited CK activity and provoked a reduced of thiol content measured by the sulfhydryl assay in all the tissues studied. Therefore, changes in energy homeostasis and motor behavior in rats treated with this organotellurium support the hypotheses that the brain is a potential target to pharmacological and toxicological effects of this compound.

Tyrosine inhibits creatine kinase activity in cerebral cortex of young rats.

Tyrosine accumulates in inborn errors of tyrosine catabolism, especially in tyrosinemia type II, where tyrosine levels are highly elevated in tissues and physiological fluids of affected patients. Tyrosinemia type II is a disorder of autosomal recessive inheritance characterized by neurological symptoms similar to those observed in patients with creatine deficiency syndromes. Considering that the mechanisms of brain damage in these disorders are poorly known, in the present study our main objective was to investigate the in vivo and in vitro effects of different concentrations and preincubation times of tyrosine on cytosolic and mitochondrial creatine kinase activities of the cerebral cortex from 14-day-old Wistar rats. The cytosolic CK was reduced by 15% at 1 mM and 32% at 2 mM tyrosine. Similarly, the mitochondrial CK was inhibited by 15% at 1 mM and 22% at 2 mM tyrosine. We observed that the inhibition caused by tyrosine was concentration-dependent and was prevented by reduced glutathione. Results also indicated that mitochondrial, but not cytosolic creatine kinase activity was inhibited by tyrosine in a time-dependent way. Finally, a single injection of L-Tyrosine methyl ester administered i.p. decreased cytosolic (31%) and mitochondrial (18%) creatine kinase activities of brain cortex from rats. Considering that creatine kinase is an enzyme dependent of thiol residues for its function and tyrosine induces oxidative stress, the results suggest that the inhibition caused by tyrosine might occur by oxidation of essential sulfhydryl groups of the enzyme. In case this also occurs in patients with tyrosinemia, it is possible that creatine kinase inhibition may contribute to the neurological dysfunction characteristic of tyrosinemia.

The organochalcogen 3-methyl-1-phenyl-2-(phenylseleno)oct-2-en-1-one induces oxidative stress in heart, liver, and kidney of rats.

The objective of this study was to investigate the in vitro effects of the organochalcogen 3-methyl-1-phenyl-2-(phenylseleno)oct-2-en-1-one on some parameters of oxidative stress in liver, kidney, and heart of 10-day-old rats. The homogenates of liver, kidney, and heart were incubated for 1 h in the absence (control) or in the presence of 1, 10, or 30 µM of the organoselenium and thiobarbituric acid reactive substances, carbonyl, and the activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) were measured. First, we tested the influence of the compound on 1,1-diphenyl-2-picrylhydrazyl (DPPH(•)) radical scavenging and verified that the organochalcogen did not have any antioxidant properties. We observed an increase of lipid peroxidation in all concentrations tested in heart and kidney, while in liver only in the concentrations of 10 and 30 µM. Moreover, we also verified an enhance of protein oxidation in the concentrations of 10 and 30 µM in kidney. On the other hand, the compound caused a reduction on the activity of CAT in heart (10 and 30 µM), liver (30 µM), and kidney (30 µM). The activity of SOD was increased in heart (10 and 30 µM), while in liver (30 µM) and in kidney (10 and 30 µM) the activity was reduced. Our findings indicate that this organoselenium compound induces oxidative stress in liver, heart, and kidney of immature rats, collaborating to the fact that these tissues are potential targets for the organochalcogen action.

Inhibition of creatine kinase activity by 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one in the cerebral cortex and cerebellum of young rats.

In the present study, we investigated the potential in vitro toxicity of the tellurium compound 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one on creatine kinase activity in cerebral cortex and cerebellum of 30-day-old Wistar rats. First, enriched mitochondrial and cytosolic fractions from the two tissues were pre-incubated for 30 min in the presence or absence of 1, 5 or 20 microm of organotellurium and the creatine kinase activity was measured. The organochalcogen reduced creatine kinase activity in a concentration-dependent pattern in the two tissues studied. Furthermore, the enzyme activity was performed after pre-incubation for 30, 60 or 90 min in the presence of 5 microm of the organotellurium. The compound inhibited creatine kinase activity in a time-dependent way in the enriched mitochondrial fraction of both tissues, but not in the cytosolic fraction, indicating different mechanisms for the organochalcogen in the mitochondrial and in the cytosolic creatine kinase. Pre-incubation of tellurium compound with reduced glutathione suggests that creatine kinase activity inhibition might be caused by direct interaction with thiol groups or by oxidative stress. Our findings suggest that creatine kinase inhibition may be one of the mechanisms by which this organotellurium could cause toxicity to the rat brain.